Cryovolcanism on Ceres
Dawn Framing Cameras observations of surface structures on Ceres
NASA’s Discovery Mission Dawn returned a wealth of information from the largest body in the main asteroid belt, the dwarf planet Ceres. This object is the most water-rich body in the inner solar system (in relative abundance) and may represent the population of planetesimals that brought volatiles and organics to the inner solar system. The partially differentiated ~ 950 km diameter object was mapped from different orbits between 2015 and 2018. The returned data surprisingly revealed a potential ocean world with regional brine reservoirs at larger depths and a young geological activity.
The Framing Camera, a scientific instrument build and operated by the Max Planck Institute for Solar System Research, imaged the cerean surface in seven colour filters and one clear filter (0.4 – 1.0 µm), leading to a global colour filter mapping of the surface at a pixel scale of ~140 m during the High Altitude Mapping Orbit (HAMO) and at ~35 m pixel scale for the clear filter during the Low Altitude Mapping Orbit (LAMO). In addition, during its extended mission, clear filter images of the Occator and Urvara crater have been obtained with a pixel scale of up to ~3 m. The high-resolution FC imagery is completed by spectral information of the Visible and Infrared Spectrometer (VIR) obtained in the wavelength range 1.0 – 4.1 µm at a spatial scale of ~95 m from LAMO.
The Dawn mission revealed local evolutionary processes at surprisingly recent epochs as, for example, at Occator crater where cryo-volcanism shaped the cerean surface. Occator is a relatively young (~22 Ma) complex impact crater which displays bright salty deposits (faculae) across its floor whose origins are due to ascending brines from large depth. During the past years we were able to show that these salty deposits are significantly younger than the impact crater itself and that cryo-volcanic activity could be still ongoing on a low intensity level. Less apparent are indicators of past cryo-volcanic activity at other sites of mostly older age, which are more affected by erosion, surface relaxation, and ejecta blanketing. However, it has been suggested that among larger impacts, Occator-like late activity was prevalent, and is still traceable thorough the analyses of colour and spectral data.
The PhD project is intended to search for further signs of cryo-volcanism on the surface of Ceres by using newly calibrated color imaging data of unprecedented accuracy. The main goal is to help understand whether a global brine layer at about 40 km depth at the crust–mantle boundary exists and whether cryo-volcanic activity is a past or also a present phenomenon. The results gathered from the remote sensed data can be further complemented by characterizing analog meteoritic samples with different laboratory techniques.
In this PhD project the candidate will learn to work with sophisticated software tools (e.g. ISIS, ENVI, IDL, ArcGIS) analyzing reflectance spectroscopic and imaging data that have been returned by the Dawn mission. In addition, the candidate will get familiar with meteoritic sample preparation as well as the chemical and mineralogical characterization techniques of these samples. The PhD project is embedded in a local and international team of scientist from different fields.
